Link to issue number:

Closes #14973

Summary of the issue:

Add-ons installed from the add-on store used the untranslated add-on store JSON strings.
As of #15137, only add-ons that were installed from an external source had translated strings.

Description of user facing changes

Add-ons installed from the add-on store will have translated strings.

Description of development approach

Create a separate model for add-ons fetched from the add-on store, and add-ons cached after being installed from the add-on store.
Data fetched from the add-on store should be translated. Installed cached data for an add-on will be whatever language is used when the fetched add-on store data is cached. As such, we should defer to the translated manifests for installed add-ons.

Testing strategy:

Check that an add-on installed from the add-on store has translated strings

Known issues with pull request:

None

Change log entries:

N/A

Code Review Checklist:

• Pull Request description:
  • description is up to date
  • change log entries
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• API is compatible with existing add-ons.
• Documentation:
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• Security precautions taken.